startup-financial-model（启动财务模型）

Startup Financial Model Skill

Build complete 3-statement financial models for early-stage and growth-stage startups. This skill guides Sam Ledger through constructing investor-ready models, running scenario analysis, calculating burn/runway, and producing structured output ready for Excel or Google Sheets.

When to Use This Skill

Trigger phrases:

• "Build a financial model for…"
• "How much runway do we have?"
• "Create a 3-statement model"
• "What's our burn rate?"
• "Model out our revenue forecast"
• "Investor asks for a 3-year model"
• "Show me base/bull/bear scenarios"

NOT for:

• Public company valuation (DCF, comps) — different methodology
• Tax filing or tax planning — use compliance workflows
• Historical bookkeeping — use QBO/accounting integrations
• Real-time actuals syncing — use qbo-automation skill
• Cap table modeling — use cap-table-manager skill

Core Model Components

1. Revenue Model

Start by identifying the revenue driver type:

Revenue forecasting inputs to collect:

- Current MRR/revenue (starting point)
- Monthly or annual growth rate assumption
- Churn rate (monthly, for subscription)
- New customer acquisition volume (monthly)
- ARPU / ACV (average revenue per user/contract value)
- Expansion/upsell rate (if applicable)
- Seasonality adjustments (if applicable)

SaaS Revenue Formula (monthly):

MRR(t) = MRR(t-1) 
        + New MRR (new customers × ARPU)
        + Expansion MRR
        - Churned MRR (MRR(t-1) × churn rate)

2. Expense Model (P&L)

Expense categories to model:

COGS (Cost of Goods Sold):

• Hosting/infrastructure (% of revenue or fixed)
• Payment processing fees (% of revenue)
• Customer support costs (headcount-driven)

Operating Expenses:

Sales & Marketing:
  - Paid acquisition (CAC budget)
  - Sales team salaries + commission
  - Marketing tools / events

Research & Development:
  - Engineering salaries (FTE × loaded cost)
  - Contractor/freelance dev costs
  - Tools and licenses

General & Administrative:
  - Executive salaries
  - Legal, accounting, compliance
  - Office / remote infrastructure
  - Insurance

Headcount Planning Template:

Role | Start Date | Monthly Salary | Benefits % | Total Loaded Cost
-----|------------|----------------|------------|------------------
CTO  | Jan 2026   | $15,000        | 25%        | $18,750
Eng  | Mar 2026   | $10,000        | 25%        | $12,500
...

3. P&L Statement

Revenue
  - COGS
= Gross Profit
  Gross Margin %

  - S&M Expense
  - R&D Expense
  - G&A Expense
= EBITDA
  EBITDA Margin %

  - Depreciation & Amortization
= EBIT

  - Interest Expense
= EBT (Earnings Before Tax)

  - Income Tax
= Net Income

4. Cash Flow Statement

Three sections:

Operating Activities:
  Net Income
  + D&A (non-cash add-back)
  ± Changes in Working Capital:
    - Accounts Receivable (increase = use of cash)
    - Accounts Payable (increase = source of cash)
    - Deferred Revenue (SaaS advance payments = source)
    - Prepaid Expenses

Investing Activities:
  - CapEx (equipment, IP capitalization)
  - Security deposits

Financing Activities:
  + Capital raises (equity funding rounds)
  + Debt proceeds
  - Debt repayments
  - Dividends (rare for startups)

= Net Change in Cash
+ Beginning Cash Balance
= Ending Cash Balance

5. Balance Sheet

ASSETS
Current Assets:
  Cash & Cash Equivalents  ← from Cash Flow ending balance
  Accounts Receivable
  Prepaid Expenses

Non-Current Assets:
  PP&E (net of depreciation)
  Intangibles / Capitalized Software

LIABILITIES
Current Liabilities:
  Accounts Payable
  Deferred Revenue
  Accrued Expenses

Non-Current Liabilities:
  Long-term Debt / Convertible Notes

EQUITY
  Paid-in Capital (cumulative fundraising)
  Retained Earnings (cumulative Net Income)
  Total Equity

CHECK: Assets = Liabilities + Equity ← must balance

Burn Rate & Runway Calculator

Gross Burn Rate

Gross Burn = Total Monthly Cash Outflows
           = COGS + OpEx (cash basis, pre-revenue)

Net Burn Rate

Net Burn = Gross Burn - Revenue Collected
         = Monthly cash out - monthly cash in

Runway

Runway (months) = Current Cash Balance ÷ Net Burn Rate

Example:
  Cash: $1,200,000
  Net Burn: $80,000/month
  Runway: 15 months

Runway with Milestones

Milestone-adjusted runway = months until Series A, profitability, or breakeven
Break-even month = month where Net Burn = $0 (revenue ≥ expenses)

Scenario Modeling

Build three scenarios with different assumptions:

Output for each scenario:

• Runway (months from today)
• Break-even month
• Cash at end of model period
• Revenue at 12/24/36 months
• Key risk: what causes bear scenario?

SaaS-Specific Metrics

When modeling SaaS businesses, include these unit economics:

LTV (Lifetime Value):
  LTV = ARPU / Monthly Churn Rate
  Example: $500 ARPU ÷ 2% churn = $25,000 LTV

CAC (Customer Acquisition Cost):
  CAC = Total S&M Spend / New Customers Acquired
  Example: $50,000 S&M ÷ 100 new customers = $500 CAC

LTV:CAC Ratio:
  Healthy = 3:1 minimum, 5:1+ strong
  $25,000 LTV ÷ $500 CAC = 50:1 (excellent)

CAC Payback Period:
  Payback = CAC / (ARPU × Gross Margin %)
  Example: $500 ÷ ($500 × 70%) = 1.4 months

Net Revenue Retention (NRR):
  NRR = (Beginning MRR + Expansion - Contraction - Churn) / Beginning MRR
  Target: >100% = expansion offsets churn

Output Format

Structured JSON for Export

When generating model output, produce structured data in this format:

{
  "model_meta": {
    "company": "Acme SaaS Inc.",
    "model_date": "2026-03-15",
    "currency": "USD",
    "period": "monthly",
    "horizon_months": 36
  },
  "assumptions": {
    "starting_mrr": 50000,
    "mom_growth_rate": 0.10,
    "monthly_churn_rate": 0.025,
    "gross_margin_pct": 0.70,
    "starting_cash": 1200000,
    "monthly_burn_base": 95000
  },
  "scenarios": {
    "base": {
      "runway_months": 15,
      "breakeven_month": 18,
      "arr_12m": 960000,
      "arr_24m": 2400000,
      "cash_end_of_model": 340000
    },
    "bear": { ... },
    "bull": { ... }
  },
  "monthly_projections": [
    {
      "month": 1,
      "mrr": 55000,
      "gross_profit": 38500,
      "total_opex": 90000,
      "ebitda": -51500,
      "net_burn": 51500,
      "cash_balance": 1148500
    },
    ...
  ]
}

Google Sheets Export Instructions

When producing a Sheets-ready model:

1. Output as CSV blocks per tab: Revenue Model, P&L, Cash Flow, Balance Sheet, Scenarios
2. Use formula notation where helpful: =B2*(1+$B$1) style references
3. Highlight assumption cells (color note: yellow = input, blue = formula)
4. Include a Dashboard tab with: Runway, MRR, Burn Rate, Gross Margin % as headline KPIs

Step-by-Step Workflow

When a user asks to build a financial model:

Step 1: Intake

Collect these inputs (ask if not provided):

□ Company name and stage (pre-seed, seed, Series A?)
□ Business model (SaaS, marketplace, services, etc.)
□ Current MRR / ARR or monthly revenue
□ Current cash balance
□ Monthly headcount and loaded cost estimate
□ Key growth assumption (growth rate, sales targets)
□ Model horizon (12, 24, or 36 months?)
□ Purpose (internal planning, investor diligence, board deck?)

Step 2: Build Revenue Forecast

• Apply driver-based model for the business type
• Calculate monthly revenue for each period
• Show MRR bridge (new / expansion / churn)

Step 3: Build Expense Model

• Headcount plan with hire dates
• COGS as % of revenue or fixed
• OpEx categories per above

Step 4: Assemble 3 Statements

• P&L from revenue and expenses
• Cash flow from P&L + working capital changes
• Balance sheet from cumulative cash flow + equity raises

Step 5: Burn & Runway

• Calculate net burn per month
• Project runway from current cash
• Identify break-even month

Step 6: Scenario Analysis

• Run base, bear, bull with varied assumptions
• Summarize: how bad does it have to get before we run out of cash?

Step 7: Output

• Structured JSON or CSV for export
• Narrative summary: key risks, milestones, funding gaps
• Investor-ready summary table

Example Usage

User: "We have $800k in the bank, burning $65k/month net, growing MRR at 8% per month from $30k base. How long is our runway and when do we break even?"

Sam's response:

Runway Analysis:

Starting MRR: $30,000 | Net Burn: $65,000/month | Cash: $800,000

Month-by-month (base case, 8% MoM growth):
  Month 1:  MRR $32,400  | Burn est. $62,500  | Cash $737,500
  Month 6:  MRR $47,600  | Burn est. $47,000  | Cash $421,000 ← near breakeven
  Month 7:  MRR $51,400  | Burn est. $44,000  | Cash $377,000 → Cash flow positive
  
Runway: ~13 months before cash hits $0 (bear) / 18+ months if growth holds (base)
Break-even: Month 6-7 at ~$50k MRR (assuming costs stay relatively flat)

Key risks:
  - Growth slows to 4%: runway drops to 9 months
  - Unexpected hiring: 2 engineers = -$25k/month → runway -4 months
  
Recommendation: Fundraise at month 8-9 (Series A prep) or hit $60k MRR as proof point first.

Integration Points

• crypto-tax-agent — for token/equity-based compensation modeling
• cap-table-manager — for equity dilution modeling alongside funding scenarios
• kpi-alert-system — set alerts when actual vs. model variance exceeds threshold
• qbo-automation — pull actuals from QuickBooks to compare against model
• report-generator — format model output into investor-ready PDF/deck

Reference: Key Formulas Cheat Sheet

Gross Margin %     = (Revenue - COGS) / Revenue × 100
Net Burn           = Cash Out - Cash In (monthly)
Runway (months)    = Cash Balance / Net Burn
MoM Growth         = (Current MRR - Prior MRR) / Prior MRR × 100
ARR                = MRR × 12
LTV                = ARPU / Churn Rate
CAC Payback        = CAC / (ARPU × Gross Margin %)
Rule of 40         = Revenue Growth % + EBITDA Margin % (target ≥ 40 for SaaS)
Magic Number       = Net New ARR / Prior Quarter S&M Spend (target > 0.75)